How to handle the POA sibling telling lies about me to our mother?

My sibling & I got into an extremely heated argument about 2 weeks ago regarding her alcoholism that she wants me to keep secret from Mom. I told her I never promised (nor would I ever) to keep a secret that enabled her to continue drinking like a back alley drunk. The Golden One was melt-down raging angry at the Black Sheep. So my sibling decided all of a sudden that I had been cheating Mom out of her nest egg. Furthermore, & the most interesting part was when my sibling made a b-line to Mom's while I happened to be on the phone w/Mom. Given Mom's alzheimer's she doesn't know how to operate the phone to hang it up. That allowed me to hear EVERYTHING my sibling said to her. If you always wanted to be that fly on the wall, be prepared for what you might hear. I listened to a well rehearsed stream of crap and lies come out of her mouth about me and that there were "thousands involved." That's such a lie. I did make one fat finger mistake on what I spend for Mom, but I had fixed that and returned the funds well over a week before this talk. My sibling lied and attempted to manipulate Mom just to get back at me for me having been angry about her drinking. I know her and I have no doubt her intentions were to get me in trouble not only with Mom, but perhaps APS, or some other authority. It was amazing hearing her go on & on & so obviously trying to manipulate Mom into taking some sort of action against me. When she was about finished I YELLED into the phone so I could be heard on the phone and listening and that I wanted the speaker put on so I could participate in the conversation. I was extremely upset and also hurt that my sibling would do this. We have been extremely close all our lives but I told her I didn't trust her because of all the lies she tells sneaking her alcohol in the house & taking nips all day until she is drooling & laying on the floor moaning, soaked in her own urine or where she had urinated on the couch, the bed, the floor, ME while I was asleep in the middle of the night. Yes, she urinated on me and is completely out of control (and she had just finished rehab 6 weeks earlier). Once on speaker phone I was able to defend myself & asked continually for proof, which she was unable to provide. We also talked about her alcoholism (my dad was one, too). Mom said she had wondered if my sister had been drinking. I don't know how she picked up on it. Mom also said that what my sister said that day sounded "forced," and very rehearsed and manipulative and she didn't believe all she was hearing. Ha ha ha. So we talked & I told her while my sibling was listening what had been going on with the drinking & urinating & how difficult it was to be a caregiver AND have to deal with the raging alcoholic I live with. It's too much & I found myself in bed for 3 days, basically unable to deal with it all at once. I dragged myself out of bed, but I'm feeling depressed and constantly on the verge of a crying jag (which I've done but doesn't help). So, she says she "just fell off the wagon" and she "has control over it." Lie. There's no such thing as an alcoholic that has control of their drinking...that's why they are....duh....alcoholics. If she'll do this 6 weeks out of rehab what can I expect next -- more lies, more urinating on everything? It's not just the combination of everything she said, it's that she did her best to betray me. Betray me. My own sister. I don't know what to do. We own a house together & the only reason she went to rehab was because I had threatened putting the house on the market & going our separate ways. The only problem with that is I can't afford to live on my own and there's not that much equity. I feel trapped. I know I can't chg her & the only choice I have is to chg myself/attitude. But how?? Suggestions, please!!! I have to sit in this living room next to her, day in and day out, knowing with certainty that hurting me is now on the table. I HATE alcohol.